The BBC reports that a fracas over the effect of the sun on the earth's climate raises the need for yet more research to determine the causes and likely consequences of global warming:

A US scientist has cast doubt on the controversial idea that the Sun has been the main contributor to climate change over the past 20 years. The Sun is known to brighten and fade from time to time, influencing temperatures on Earth. Scientists are divided over how significant a factor this is compared with what people are doing to the planet. A recent study suggests the Sun has brightened steadily over the past 20 years, accounting for half or more of the 0.3 degrees Celsius warming blamed on greenhouse gas emissions since 1980. ... What is clear, however, is that more work needs to be done to iron out uncertainties.